#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main()
{
    char str[100000] = { 0 };
    int arr[128] = { 0 };
    gets(str);
    int count = 0;
    int sz = strlen(str);
    for (int i = 0;i < sz;i++)
    {
        int tmp = (int)str[i];
        if (arr[tmp] == 0)
        {
            arr[tmp] = tmp;
            count++;
        }
    }
    printf("%d", count);
    return 0;
}